Electro-hydraulic systems are used in a variety of industrial and other applications, including the automotive industry. Electro-hydraulic systems may be defined as those involving electrical signals (e.g., an electrical input command signal) and components (e.g., solenoids) that also further involve controlled hydraulic fluid paths and/or pressures. One example may be a two-stage main pressure regulating assembly that may be used in an automatic speed change transmission, where the first stage is a pressure control solenoid (PCS) providing a pilot pressure in response to an input command (i.e., electrical signal) and where the second stage includes a spool valve configured to regulate a main fluid pressure in accordance with the pilot pressure. This is only one example and those of ordinary skill in the art will recognize a wide range of other examples of electro-hydraulic systems.
In order to design a control system for operating such an electro-hydraulic physical plant, a plant dynamics model is conventionally required. However, acquiring an accurate plant dynamics model is a very time consuming and resource intensive undertaking. In certain instances, such an undertaking is simply not possible given the real-world product development timing requirements. Conventional approaches for obtaining an accurate plant dynamics model require making a prototype of the physical part or plant. This requirement can effectively serialize the control system development process, viz. first, the physical part or plant must be made and its input/output dynamics characterized, and then second, only when accurate plant dynamics are known, can the control system design begin. This leads to slower development times.
It is known in some fields of technology to begin preliminary control algorithm development work, using computer simulations, prior to actually producing a prototype and characterizing the same, as seen by reference to Wang et al., Rapid Prototyping of ACC Algorithms with Virtual Human and Plant Models, SAE 2002 World Congress, SAE 2002-01-0516 (“Rapid Prototyping”). The Rapid Prototyping article discloses an approach for developing controls for an automotive automatic climate control (ACC) system without subjecting the vehicle to environmental tunnel testing for proper calibration of the control algorithms. While use of the approach in the Rapid Prototyping article can greatly expedite development, its reach is admittedly to only preliminary control algorithm work, and in any event does not provide any direct guidance as to applicability to electro-hydraulic systems. Moreover, electro-hydraulic systems typically include a multitude of non-linearities (e.g., variance in gain), making characterization anything but straightforward.
There is therefore a need for a method for generating a model of an electro-hydraulic system that minimizes or eliminates one or more of the problems set forth above.